Slurry drying device



Jan. 23, 1940. N. s. BORCH ET AL- SLURRY DRYING DEVICE Filed Aug. 21, 1937 3 Sheets-Sheet 2 INVENT R ul4 3fitmi ATTORNEYS,

Jan. 23, 1940. N. s. BORCH El AL SLURRY DRYING DEVICE Filed Aug; 21, 1937 3 Sheets-Sheet 5 II I l INVENTOR5 5 m MR 3M9 emmdlj ATTORNEYS I Patented Jan. 23, 1940 SLURRY DRYING DEVICE Niels Sofus Borch,- Copenhagen, and Kristian Middelboe, Frederiksberg, near Copenhagen, Denmark, assignors to'F. L. Smidth & Company, New York, N. Y., a corporation of New Jersey Application August 21, 1937, Serial No; 160,208 In Great Britain August 24, 1936 12 Claims.

v This invention relates to apparatus for drying slurry, such as cement raw slurry.

An important object of the invention is to dry slurry on conveyor elements by means of hot gases in such away that all the dried slurry can be easily removed. A further object of the invention is 'todry slurry in this way without producing much dust.

Anotherimportant object of ,the invention is bunched together while hot gases pass in contact with them, so that the slurry on the elements is closely swept by the gases, but the elements are spaced apart in the remainder of the circuit so that the dried slurry can easily be removed and fresh slurry applied to them.

Yet another object of the invention is to provide a novel form of chain curtain for use in drying slurry.

A still further object is to provide an improved form of dryingdevice in which conveying elements coated with slurry move through a passage in counter-current to hot gases and occupy substantially the whole cross-section of that passage.

Further objects will hereinafter appear.

The invention will be most clearly understood by the followingdescription of. some apparatus embodying it, when read in] conjunction. with the accompanying drawings, in which: I v

Figure 1 illustrates the first apparatus diagrammatically;

Figures 2 and 3 show details of this apparatus on an enlarged scale; 1

Figure 4 shows another apparatus diagrammatically; v f

Figure 5 illustrates diagrammaticallymodified devices for covering the conveying elements with slurry; w v

Figure 6' shows a third form of apparatus diagrammatically; I

Figures '7 and 8- show details of a chain curtain; and

Figure 9 s hows details inFigure 4. -I v Referring first to Figures 1 to 3 an endless chain curtain l is. provided and passes around rollers 2 and 3. Between these rollers there is a plate 4 and as the chain curtain passes'over this plate it is sprayed with slurry through nozzles 6 fed by a pipe 5.

Thewet curtain passes downwards from the roller 3 through a narrow passage 1 which fits the curtain so tightly to 'oifer considerable of the apparatus shown resistance to any flow of gas through the ,pas-' sage in counter-current to the curtain.

The curtain consists of .two endless chains'b connected'by cross-rods c on which helices d and rings e are hung. At regular intervals on 6 the chains there are links a different from the remaining links and furnished with rollers'f.

The drying passage is constituted by part of a flue 9, through which hot g'ases'from akiln flow. .When the chain curtain reaches the bot- 10 tom of the passage 1 the links a encounter rails '8 whichrun through the drying passage and the rollers f then, travel'along these rails; As aresult, the part'of the, chain curtain between two successive links a folds itself double, and the dis': tance, between successive links a is such that the foldsoccupy the whole cross-section of the drying passage. The bottom link g of each fold is provided with a T-shaped member hso that the leg of the T drags along the bottom'of the drying passage and cleans out this passage. As the chain curtain occupies thewhole cross-section of-the drying passage the hot gas is forced to pass through the curtain and in doingso it drys and, if it is hot enough, preheats the slurry.

In order to cause the folded curtain to move through the-drying passage 9, which is horizontal, atdriving. mechanism is provided in the form of a rotaryeccentric H to which a connecting rod is pivoted at l2, the other end of the con- "nesting rod l3 being connected to a pushing member M which slides in a straight path and moves the curtain forward through a distance equal to the, length of one linka at each stroke. The speed of this driving mechanism is synchronised with the speed of movement of the conveyor so that as each successive link a arrives in the dryingpassage the pushing member M has oneforward stroke. r

At the other end of the drying passage lithe linksa. are-simply lifted off the rails 8 asthe;

chain curtain is pulled upwards by the rollers 2 and 3. In order to remove the dried slurry. the chain curtain is struck by a beating. device l5 which consists of two rotary discs it connected together by parallel bars H on which are mounted rings 18 which act as resilient hammersMThe dried slurry falls into the part of the fluethrough which the hot gases pass on their way to the drying passage and they may slide directly down this flue into the rotary kiln.

; The whole apparatus is enclosed in a casing 20 so that the only points at which gas might escape are those where the shafts of the beat-f ing device l5 and the rollers 2 and 3 pass through it, and the pushing member l4 slides through it, and it is easy to seal these.

The beating device might become overheated by the radiation of heat from the hot gases, and it is therefore shielded by appropriately shaping the casing 23 as shown at l9. The chain curtain itself is protected from the intense heat of the hot gases in the drying passage by the coating of slurry, and when the dried slurry has been removed there is little tendency to overheat and thus damage it, because some steam is generated at the point where the slurry is sprayed on to the chain curtain and this steam flows downwards past the beating device so that the atmosphere around this device is relatively cool.

Any dust that is developed in the neighbourhood of the beating device is prevented from escaping to the atmosphere because in its passage towards the outlet end of the flue it is caught up on parts of the chain curtain where the slurry is still Wet enough to keep the apparatus substantially dust-free.

Figures 7 and 8 show a modified form of chain curtain which can be used in the apparatus shown in Figure 1. I-Ielices d are hung on cross-rods c as before. These cross-rods c are united in pairs by connecting pieces k which are welded to them, and the rigid elements or frames thus produced are linked together by links I. The cross-rods c that are to be uppermost in the drying passage carry distance piece 172 and rollers 11, the latter being arranged to slide on the main rail 8. Every other rod 0 is provided with a projection 10 arranged to strike a guide rail q in order to initiate the folding of the chain curtain.

In the modified form of apparatus shown in Figure 4 two endless chains 25 guided and driven by chain wheels 22 and 23 are provided at regular intervals with projections 24. The conveying elements, which may themselves be of any convenient form, are mounted in rigid frames 25 furnished with downwardly facing grooves or the equivalent in which the projections 24 engage. In this apparatus the slurry is picked up by the conveying elements from a slurry basin 26 into which they are caused to dip in their passage through the closed circuit. The wet elements pass through a narrow passage formed by walls 2'! and 28 and on arriving at the mouth of the drying passage are detached from the endless chains by the engagement of the cross-bars 24 of the conveying elements with abutments in the form of rails similar to the rails 8. The conveying elements are moved through the drying passage by a driving mechanism 30 similar to the mechanism I il4. At the other end of the passage the conveying elements are simply picked up by the projections 24, the elements 251) having just been picked up in this way. They are then carried past a rotary beating device 33 with hammers 34 of a similar construction to the beating device shown in Figure 1. The dried slurry falls through a passage 35.

In order to prevent the hot gases escaping through the openings 35 and 31 at which the conveying elements respectively leave and enter the drying passage weighted shutters 38, 38a, and 39 which are moved against their weights by the conveying elements themselves are provided.

Figure 9 shows one conveying element suitable for use in the apparatus of Figure 4. Cross-rods r carrying helices d are fixed in a frame 3. At the top of this there is a bail 25 arranged to engage a projection 24 on the chain 2|.

Figure 5 shows the way in which a continuous chain curtain, of the kind illustrated, for example in Figures 1 to 3, may be caused to travel through a slurry basin to pick up slurry. Chain wheels or rollers 41 and 43 are arranged outside the basin and a chain wheel or roller 42 is provided in the basin itself.

Figure 6 shows a form of apparatus in which the conveying elements move through the drying passage unden the influence of gravity. The passage 9' and rails 8' within it are inclined and at the outlet end the rails are bent upwardly at 8". This figure also illustrates another device for applying slurry. The chain curtain 48 while travelling horizontally passes beneath a wall 41. Slurry runs from a hopper 45 into a slurry trap 46 and from this on to the chain curtain, and some of it oozes through it and falls into a trough 49. Here there is a rotary body 50 with radial arms which fiings the slurry upwards out of the trough on to the underside of the curtain.

We claim:

I. In an apparatus for drying raw slurry, means forming a drying passage, conveying elements arranged to move through said passage in bunched form, means for causing said elements to move in a closed circuit including said passage, a slurry feed device formed with a feed opening through which slurry can flow under gravity, means outside said passage for causing said elements to move in open form in a substantially horizontal path beneath said opening, a trough beneath said path arranged to receive surplus slurry from said elements, means within said trough for throwing slurry upwards on to the underside of said elements, and means for causing hot gases to flow through said pasage in counter-current to said bunched elements.

2. In an apparatus for drying raw slurry, means forming a drying passage, an endless chain curtain arranged to move through said passage,

being non-obstructive to said longitudinal flow of :1

the gases throughout the cross section of the drying passage.

3. In an apparatus for drying raw slurry, the combination of a passage, means for causing hot gases to flow through the passage longitudinally 51 thereof, a plurality of conveying elements, supporting means for the elements, means for moving the supporting means to cause the elements to travel through a closed circuit which includes the passage and in the opposite direction to that of the flow of gases through the passage, means acting on the supporting means of elements entering the passage to cause the elements to form closely grouped series extending transversely of the passage, the elements in the series occupying substantially the entire cross section of the passage, the moving means causing the elements traveling through that part of the circuit outside the passage to lie in a single series extending in the direction of travel of the supporting means, and means for coating the elements with slurry before they enter the passage, the series of coated elements within the passage being permeable by the gases flowing through the passage.

4. In apparatus for drying raw slurry, the com- 2,187,800" bination of a passage, means for causingjhot gases bunched elements within'the passage being per l to flow through'the passage, conveying elements movable through-the passage in close succession to one another and in a direction opposite to that of the gas flow, the group of conveying elements within the passage occupying substantially the entire crosssection thereof, an endless conveyor operable to pick up the elements at one end of the passage and carry them to the other end thereof, the elements carried by the conveyor lying farther apart thanlthose within the passage, means for disengaging elements from the conveyor at said other end of the passage to permit them to pass therethrough, and means for coatingthe elements, with slurry while they are being carried by the conveyor, the group of coated elements within the passage being permeable by the gases flowing'through the passage.

5. In apparatus for drying raw slurry, the combination of a passage, means for causing hot gases to flow longitudinally through the passage, a plurality of conveying elements movable through the passage in a direction opposite to thatv in which the'gas is'flowing, the elements within'the passage lying close to one another and occupying substantially the entire cross section of the passage, an endless conveyor operable to pick up elements at one end of the passage, remove them from the passage, and return them to the passage at the other end thereof, means for disengaging the elements from the conveyor at said other end of the passage topermit them to be moved through the passage, means for moving through the passage the elements which have been disengaged from the conveyor, and means for coating the elements with slurrywhile they are carried by the conveyor, the group of coated elements within the passage being permeable by the gases flowing through the passage.

6. In apparatus for drying raw slurry, the combination of a passage, means for causing hot gases to flow through the passagefa plurality of conveying elements movable through the passage in a direction opposite to,that in which the gas.

is flowing, the elements .withinthe passage lying close to one another and occupying substantially the entire cross section of the passage, an endless conveyor operable to pick up elements at one end of-the passage, remove} them from the passage,

and return them to the passage at theother end thereof, means for disengaging the elements from the conveyor atsaid other end of the passage to permit them to be moved through the passage, means for moving elements disengaged from the conveyor through the passage with a step by step movement, and means for coating the elements with slurry while they are carried by the cor'1- veyor, the'group of coated elements within the passage being permeable by the gases flowing through the passage. v r

7. In apparatus for drying raw slurry, the combination of a passage, a plurality of conveying elements, means for moving the elements in a closed circuit during which they pass through the passage, means adjacent the point where the elements. enter the passage for bun'ching them togetherythe elements when so bunched occupying substantially the entire cross section of the passage, -means for spacing the elements apart adjacent the point where they leave the passage,

means for coating the elements with slurry while they are spaced apart, and means for causing hot gases to flow longitudinally through the passage in a direction opposite to that of the elements moving through the passage, the group of meable by the flowing gases. I

8. In'anapparatus for drying raw slurry, the

combination of a passage, means for causing hot gases to flow through the passage longitudinally thereof, a plurality of conveyingelements, supporting means for the elements, means for moving the supporting means to cause the elements to travel through a closed circuit which includes the passage and in the opposite direction to that of the flow of gases through the passage, means acting on the supporting means of elements entering the passage to cause the elements to form closely grouped series extending substantially transversely of the passage, the elements in the series occupying substantially the entire cross section of the passage, the movingmeans causing the elements traveling through that part of the circuit'outside the passage to lie in a single series extending in the direction of travel of the supporting means, and nozzles for'discharging slurry upon the spaced apart elements before they enter the, passage, the series of coated elements within, the passage being permeable by the gases flowing v of the flow of gases through the passage, means acting on the supporting means of elements entering the passage to cause the'elements to form closely grouped series extending substantially transversely of the passage, the elements in the series occupying substantially the entire cross section of the passage, the moving means causing the elements traveling through that part of the circuitoutside' the passage to lie ina single series extending in the direction of travel of the supporting means, and a vessel outside the passage containing slurry through which the elements are moved by the moving means, the series of coated elements within the passage being permeable by the gases flowing through the passage.

10. In an apparatus for drying raw .slurry, the combination of a passage, means for causing hot gases to flow through the passage longitudinally thereof, a pluralityv of conveying-elements, supporting means for the elements, .means for moving the supporting mean's to cause the elements to travel through a closed circuit which includesthe passage and in the opposite direction to that of the flow of gases through the passage, means acting on the supporting means of elements entering the passage to cause the elements that part of the circuit outside the passage to lie in a single series extending in the direction of travel of the supporting means, means for coating the elements with slurry before they enter the passage, the series of coated elements within the passage being permeable by the gases flowing I through the passage, and means for agitating the elements to knock driedslurry from them, the the agitating means being disposed between the point where the elements leave the passage and the coating means. I

11. In an apparatus for drying raw slurry, the combination of a passage, means for causing hot gases to flow through the passage longitudinally cross section of the passage, the moving means causing the elements traveling through that part of the circuit outside the passage to lie in a single series extending in the direction of travel of the supporting means, means for coating the elements with slurry before they enter the passage, the series of coated elements within the passage being permeable by the gases flowing through the passage, and means for knocking dried slurry from the elements, said means being disposed between the point where the elements leave the passage and the coating means and including a pluralityof resilient hammers.

12. In an apparatus for drying raw slurry, the combination of a passage, means for causing hot gases to flow through the passage longitudinally thereof, an endless conveyor having a portion lying within the passage, a plurality of conveying elements mounted on the conveyor, the conveyor having spaced projections thereon, means within the passage engageable by the projections and causing those portions of the conveyor carrying the projections to lie close together, the portions of the conveyor between the projections extending across the passage with the conveying elements carried thereby occupying substantially the entire cross section of the passage, and means outside the passage for applying slurry to the conveying elements, the groupof coated elements Within the passage being permeable by the gases flowing through the passage.

KRISTIAN MIDDELBOE. NIELS SOFUS BORCH. 

